Makefile.am: Fix msvc dir not being included in make dist

libusbx.git commit a8a80b60a14e3a8269e42dedf34fda66da8e0e50

Author: pbatard

Makefile.am

@@ -2,7 +2,7 @@ AUTOMAKE_OPTIONS = dist-bzip2 no-dist-gzip
 ACLOCAL_AMFLAGS = -I m4
 DISTCLEANFILES = libusb-1.0.pc
 MAINTAINERCLEANFILES = ChangeLog
-EXTRA_DIST = TODO PORTING
+EXTRA_DIST = TODO PORTING msvc
 SUBDIRS = libusb doc
 
 if BUILD_EXAMPLES